1. Field of the Invention
The present invention relates to a portable electronic appliance and a battery and, more particularly, to a portable electronic appliance capable of using a battery as a power source and a battery capable of being used as a power source.
2. Description of the Related Art
Many of portable electronic appliances such as digital cameras are capable of operating on a detachable battery for their portability and use AA batteries which are immediately available. AA batteries include many kinds, e.g., manganese batteries, alkaline batteries and lithium batteries formed as primary batteries, and nickel-cadmium batteries and nickel metal hydride batteries formed as secondary batteries.
All these AA batteries are identical in shape to each other. Therefore, it is difficult, for example, for a digital camera using an AA battery as a power source to identify the kind of battery when the battery used therein is changed. In an electronic product, a battery remaining voltage at which a remaining battery energy warning sign should be displayed is set as a value suitable for the kind of a battery packaged with the product when the product is sold. If a different kind of battery is used, the remaining battery energy warning sign according to the characteristics of the battery cannot be provided. For example, on a portable electronic appliance product with which an alkaline battery is packaged, a remaining energy warning sign matching the characteristics of the battery is set. If a nickel metal hydride battery is used in the portable electronic appliance, there is a possibility of the electronic appliance becoming unable to perform photography immediately after the remaining energy warning sign has been displayed due to the difference between the characteristics of the batteries.
Batteries produced by different manufacturers vary in capacity even if they are of the same kind and equal in size. Therefore, there is a possibility of batteries differing in life even from the same remaining voltage.
On the other hand, a scheme has recently been started to establish a system in which a product is provided with a wireless tag containing information on the product and the information in the wireless tag is read with a reader to be used for product management or the like.
Japanese Patent Application Publication No. 2000-22578 discloses a proposition relating to an ID card for input/output management using a wireless tag and to a stock management system. Japanese Patent Application Publication No. 5-135804 discloses means for discriminating secondary battery packs. However, either or the arts disclosed in these publications is not a solution of the above-described problem.
In a case where a power control setting according to the kind of a battery is stored in an appliance, troublesome operations are required such that it is necessary for a user to check the kind of battery and to make a power control setting each time the battery is changed.
In some case of use of a secondary battery in a portable electronic appliance, the portable electronic appliance itself has the function of charging the secondary battery. Even in such a case, however, the portable electronic appliance is incapable of discriminating a battery charged not so many times and a battery charged several hundred times from each other since it has no means for accurately determining the number of times the secondary battery is charged, and a user must keep in memory the number of times the battery is charged.
Therefore, in a case where a secondary battery for a portable electronic appliance is used a number of times closer to a number of times considered a battery performance limit such that the battery degrades in characteristics, there is a possibility of the degraded condition of the battery being mistaken as degradation in performance and failure of the portable electronic appliance.